In a communication device such as a portable telephone, a high frequency switch module has been hitherto used to connect a receiving circuit to an antenna and to connect a transmitting circuit to an antenna. In such a high frequency switch module, for the purpose of obtaining the compact and light-weight communication device itself, a plurality of circuit elements are partly formed on dielectric substrates to have a dielectric laminated structure body (harmonic circuit board) and remaining circuit elements are formed as chip elements which are mounted on the outer surface of the dielectric laminated structure body to constitute a unit with a complex structure (Refer to JP-A-6-204912 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”)).
For instance, as disclosed in JP-A-8-97743, in the well-known high frequency switch of this type, an anode of a first diode is connected to a transmitting circuit through a capacitor and the anode of the first diode is grounded through a series circuit having a first stripline serving as a choke coil and a capacitor. A first control terminal is connected to an intermediate point of the first stripline and the capacitor. To the first control terminal, a control circuit for switching the high frequency switch is connected. Further, a cathode of the first diode is connected to an antenna through another capacitor. A receiving circuit is connected to the antenna through the another capacitor and a series circuit including a second stripline and a capacitor. To an intermediate point of the second stripline and the capacitor, an anode of a second diode is connected. A cathode of the second diode is grounded through the capacitor. A second control terminal is connected to an intermediate point of the second stripline and the capacitor. To the second control terminal, a control circuit for switching the high frequency switch is connected.
The high frequency switch constructed as described above is adapted to control bias voltage applied to the first and second control terminals to switch a transmitting signal and a receiving signal.
Further, in JP-A-8-97743, there is proposed a structure that the high frequency switching circuit elements and filter circuit elements of the above-described construction are formed on a plurality of dielectric substrates except the diodes which form a high frequency device among the high frequency switching circuit elements, the diodes are formed as chip elements and the diode chip elements are mounted on the lamination body composed of the plural dielectric substrates.